Sculptor Andile Dyalvane took a break from his nearby ceramics studio to join the group drawing sessions. “Drawing is my first love,” says Mr. Dyalvane. “It’s a bit refreshing to see people’s different styles and meet other artists.”

Three years ago, Paballo Ya Batho (Feeding the People), a nonprofit serving Johannesburg’s homeless population, needed a pickup truck. Taking inspiration from a New York event, David Chong decided to hold an art auction with lots of drawings for sale on one night.

Nobody would mistake the annual event for an evening at Sotheby’s.

Hundreds of drawings pegged to clotheslines revealed some very carefully rendered scenes, and a lot that were just, well, doodles. No matter. The sheets, roughly the size of a 5-by-8-inch card, were donated and then auctioned for R100 ($12.75). With no curation and standard pricing, the event democratizes the roles that normally characterize the art world.